Bernie Sanders called on Hillary Clinton to commit to three additional debates as a condition for asking the party to sanction a New Hampshire debate scheduled for Feb. 4.

The New Hampshire Union Leader and MSNBC have scheduled a Democratic presidential debate five days before that state's primary outside the official framework of the party.

Sanders declined to take part because the debate is not sanctioned by the Democratic National Committee. The committee has said any candidate who takes part in an unsanctioned debate risks being disinvited from future debates.

USA Today reported that, "Jennifer Palmieri, a Clinton spokeswoman, told the Union Leader that Clinton would be happy to participate 'if the other candidates agree, which would allow the DNC to sanction the debate.'” Former Maryland Gov. Martin O'Malle, has accepted the invitation.

In a statement issued Wednesday night, Sanders campaign manager Jeff Weaver said, “From the beginning of this campaign Sen. Sanders has called for more debates. Secretary Clinton has not. Now she is asking to change the rules to schedule a debate next week that is not sanctioned by the DNC. Why is that? The answer is obvious. The dynamics of the race have changed and Sen. Sanders has significant momentum."

Clinton's lead over Sanders in the national polls has eroded this month, and in Iowa, where she once held a commanding lead, the former secretary of state and the senator from Vermont are tied for the caucus to be held on Monday. Sanders also has extended his lead in the Feb. 9 New Hampshire primary.

"Sen. Sanders is happy to have more debates but we are not going to schedule them on an ad hoc basis at the whim of the Clinton campaign," Weaver said, calling for the additional debates to be held in March, April and May, and "none on a Friday, Saturday or holiday weekend."

DNC Chairwoman Debbie Wasserman Schultz has been criticized for scheduling only seven debates among party candidates, compared to 12 for the Republicans. Many critics say that Democratic debates have been scheduled at times, such as weekends and near holidays, when fewer people are likely to tune in.

"If the Clinton campaign will commit to this schedule, we would ask the DNC to arrange a debate in New Hampshire on Feb. 4,” Weaver said.